Regulation and control system
Two systems of the body are responsible for regulation and control: the nervous system and the hormonal system.
Nervous system
The nervous system is a complex information processing and communication system. A distinction is made between the central nervous system (CNS: brain and spinal cord) and the peripheral nervous system (PNS: nerve fibres that connect the CNS to the periphery of the body).
Protected by the bony skull and the spinal column, the brain and spinal cord, the main parts of the central nervous system, receive a large amount of different information. This information is transmitted via the sensory nerves. The motor nerve (motor neurone), which transmits the triggering impulses from the central nervous system (brain and spinal cord) to the muscle, controls muscle contraction.
Nerve fibre (neuron)
A nerve fibre (neuron) consists of a cell body, dendrites and an axon. The cell body is responsible for supplying the neuron. The connection points between two neurons or to the signal receivers, such as muscle fibres, are called synapses. The dendrites are filled with synapses and thus form the link to other neurones. The line leading from the neuron forms the axon, which is either connected to other neurons or to another signal receiver. The fastest neurons have a transmission speed of 80m/s and control the fast muscle fibres (FT fibres).
Motor unit (mU)
This term refers to a motor neuron whose axon is connected to a muscle fibre via a motor end plate. There are slow and fast motor units. Slow motor neurones are used for fine motor skills and everyday activities. The fast motor units are used for explosive movements with high force input, such as jumping and reactive actions. The use of these fast motor skills can be trained using exercises with high resistance and rapid execution (plyometric training).
Hormone system
The body's second control system is the hormone system. Controlled hierarchically via feedback processes, hormones are used to regulate the genetic activity of target cells or metabolic activity. The hormones are distributed throughout the body via the bloodstream or cell tissue. If a cell is equipped with a corresponding hormone receptor, a reaction can be triggered. This form of distribution means that the hormone system regulates more slowly than the nervous system, but the triggered processes usually last longer. The hormone system is therefore primarily responsible for controlling processes that can be ramped up slowly and then have to be maintained for longer (growth, increased metabolic activity during stress, etc.).
There are two types of hormones, the production of which is distributed to different organs in the body. Glandular hormones reach their destination via the bloodstream and are (mainly) produced in the following glands:
pituitary gland (e.g. somatotropin = growth hormone)
thyroid/parathyroid gland (e.g. thyroxine, calcitonin)
pancreas (e.g. insulin, glucagon)
sdrenal medulla/adrenal cortex (e.g. adrenaline, cortisone)
testicles - men (e.g. testosterone); ovaries, placenta - women (e.g. oestrogen, progesterone)
Tissue hormones are produced directly in cells that are distributed throughout the tissue. They either act via the bloodstream or trigger processes in neighbouring cells. Important tissue hormones are cytokines, which regulate the growth of cells, their differentiation and function.
More info:
Training explained - Handbook of training theory (Jost Hegner):
Regulation and control systems